Re: Seeking a KVM benchmark

Paolo Bonzini
2014-11-12T15:52:06Z

On 12/11/2014 16:32, Gleb Natapov wrote:
> > > > userspace exit, urn 17560 17726 17628 17572 17417
> > > > lightweight exit, urn 3316 3342 3342 3319 3328
> > > > userspace exit, LOAD_EFER, guest!=host 12200 11772 12130 12164 12327
> > > > lightweight exit, LOAD_EFER, guest!=host 3214 3220 3238 3218 3337
> > > > userspace exit, LOAD_EFER, guest=host 11983 11780 11920 11919 12040
> > > > lightweight exit, LOAD_EFER, guest=host 3178 3193 3193 3187 3220
> > >
> > > Is this with Andy's patch that skips LOAD_EFER when guest=host, or the one
> > > that always switch LOAD_EFER?
> >
> > Skip LOAD_EFER when guest=host.
>
> So guest=host is a little bit better than guest!=host so looks like
> skipping LOAD_EFER helps, but why "lightweight exit, urn" worse than
> guest=host though, it should be exactly the same as long as NX bit is
> the same in urn test, no?

I don't know---it is very much reproducible though. It is not my
machine so I cannot run perf on it, but I can try to find a similar one
in the next few days.

Paolo